[reaction: see text] Chloral or its hydrate undergoes the carbon-carbon bond-formation reaction with various optically active imines in the absence of any additive, followed by hydrolysis, to produce the corresponding beta-trichloromethyl-beta-hydroxy ketones in good yields with high enantioselectivities. In addition, the products with higher ee values were obtained by a simple recrystallization process
Imines are reduced into the corresponding amines in high yields by Hantzschester in the presence of silicagel. The reduction shows high chemoselectivity and stereoselectivity. Reduction of α,β-unsaturated imines proceeds with high regioselectivity to yield allylic amines (1,2-reduction products).
Diastereoselective nucleophilic additions to imines attached to tricarbonyl(arene)chromium moieties
作者:Dorothy M. David、Leon A. P. Kane-Maguire、Stephen G. Pyne
DOI:10.1039/dt9940000289
日期:——
A range of imine complexes has been prepared which possess planar chirality associated with the attached tricarbonyl(1,2-disubstituted arene)chromium moiety. Nucleophilic addition to the imine group of these complexes occurs with high diastereoselectivity, providing an efficient route to the asymmetric synthesis of chiral amines. The stereochemical outcome of the additions may be rationalized in terms
Asymmetric reduction of enantiopure imines with zinc borohydride: stereoselective synthesis of chiral amines
作者:Cristina Cimarelli、Gianni Palmieri
DOI:10.1016/s0957-4166(00)00209-3
日期:2000.6
The first application of zincborohydride in the reduction of enantiopure imines for the stereoselective preparation of both the enantiomers of secondary amines is described. A possible explanation of the stereoselectivity and of the reaction mechanism is suggested on the basis of theoretical calculations.
methods available till now. The sense of asymmetricinduction has been explained and confirmed in agreement with the results previously obtained by hydride reduction of the same substrates. In some cases this procedure is complementary to the reductive one, allowing the preparation of the diastereomers less abundant in the reduction. The reaction allows the synthesis of one or the other of the two diastereomers